1. Field of Invention
The present invention relates to an optical mouse, and more particularly to a lift detection method for an optical mouse and an optical mouse with a lift detection function.
2. Related Art
With the increasing popularization of personal computers, various types of computer peripheral products are increasingly proposed to meet different requirements of the consumers, among which the mouse capable of controlling the motion of the cursor on the computer screen is the most widely used. According to its motion detection modes, the mouse can be classified into two types, namely, non-optical mechanism and optical mechanism. The non-optical mechanism performs motion detection through the rolling of the spherical scroll wheel in the bottom portion of the mouse. The optical mechanism performs motion detection by capturing an image reflected by the desktop with an image sensor.
The mouse using the optical mechanism is generally referred to as an optical mouse. In the optical mouse, an optical source, for example, a light emitting diode (LED), formed at the bottom side of the mouse emits light on the desktop, and a 2D image sensor is used to capture a special pattern formed by the micro texture of the desktop irradiated by the optical source. Thus, the change of the captured image pattern caused by the motion of the mouse is converted into a displacement according to a corresponding image processing mechanism, so as to appropriately reflect the amount of motion and direction of the cursor on the computer screen.
When the optical mouse is lifted from the working plane, an error may occur. That is to say, when the optical mouse in an inactive state is lifted from the working plane, the image sensor may detect an image formed by an external optical source and irrelevant to the motion of the optical mouse, and compute a false motion value according to the image irrelevant to the motion. Further, due to the detection of the image irrelevant to the motion of the optical mouse, the optical mouse in a power-saving state is activated by mistake, thus wasting the power consumption.
In the current designs of the lift detection function of the optical mouse, for some designs, an additional optical source and optical sensor are disposed near the original optical module, to detect the distance between the original optical mouse and the working plane, thereby determining whether the original optical mouse is lifted from the working plane. However, in the above design method, an additional set of optical sensing modules are added, thereby increasing the manufacturing cost of the optical mouse, and as most of the added optical sensing modules are formed by electronic components, the lifetime of the mouse is limited, so that the optical mouse still needs to be improved.